Engine throttle control



Feb. l6, 1937. s. R. PUFFER ENGINE THROTTLE CONTROL Filed July 25, 1934 Inventor. SarnLxel RFuf'fer: by W Hi Attorney.

. Patented Feb. 16, 1931 UNITED STATES PATENT OFFICE sworn 'nmo-rna cou'mor.

York

Application July 25, 1934, Serial No. 736,852

16Claima The present invention relates to engine control mechanisms for controlling a regulating or controlelementofanengineinresponsetocertain conditions. By engines I mean both reciproeating and rotary, as well as stationary engines, such as combustion engines, turbines, and boilers to which an actuating fiuid or substance is supplied for operating such engines. By regulatingelements" I mean, for instance, a valve for controlling the supply or the flow of actuating fluid or substance to such engines, and by certain operating conditions are meant conditions pertaining to the controlled engines, for instance, the temperature of such engines and the pressure ii at which actuating fluid or substance is supplied to the engines, as well as conditions such as temperature and pressure pertaining to other engines associated with the controlled engines, and finally, conditions pertaining to the environment of such engines in general, such as temperature and pressure of the atmosphere. More specifically, the invention relates to the kind of control mechanisms for automatically and manually controlling the regulating element or elements of g an engine to normally operate the engine at maximum safety and greatest efilciency, and permitting at any time d'eviationfrom such maximum safety and greatest efilclency operation at the will of the operator. The invention is particul'arly advantageous and will be described hereinafter in connection with supercharged, internal combustion engines as are used for the propelling of aircrafts, although it is not necessarily limited thereto.

The general object of my invention is to provide an improved construction and arrangement of the kind of engine control mechanisms above specified. A more specific object of my inventionls to provide a manual and automatic engine 40 control mechanism with which the automatic control of an engine becomes effective instantly within a certain range of load control as a certain condition, for instance the temperature of the engine, changes.

For a consideration of what I consider to be novel and my invention, attention is directed to the following description and the claims appended'thereto in connection-with the accompanying drawing which forms a part of my specification.

In the drawing I have shown in Fig. l, by way of example, a diagrammatic view of an arrangement embodying my invention in connection with r (cl. Isa-say of Hg. 2; list. 4 and 5 show certain elements of Pig. 2 in different operating positions; and Fig.

6 is a detail view of a dog arrangement of l 'ig. 2. The arrangement of Fig. 1 comprises a cylinder structure II which may be a single or a plurality 5 of cylinders to which a mixture of fuel and compressed air is supplied through a manifold II. The latter receives such mixture of fuel and compressed air from a carburetor and a mperchsrger (not shown) connected in series to the manifold 10 by a conduit II. A throttle valve II is dispolc within the conduit I! for controlling the fiow of fuel and compressed air to the cylinder or cylinders II. The valve It is connected in a short arm II, which latter is pivoted to one end of a 15 link II. The other end of the link II is pivoted to a connecting portion It of a manually controllable or movable element or lev'er II. An intermediate annular portion ll of the lever I1 is rotatably supported, as will be described more go in detail hereafter. The upper portion of the lever is provided with a manually operable handle y it. Movement of the handle to the left causes closing of the valve l3, and movement to the right causes opening of the valve ll. The arrange- 25 ment is such that the lever ll may be moved manually at any time and in any direction between closing and full opening position of the valve l3.

Regarding the automatic control of the valve so it, I have indicated in the present instance an apparatus or means for controlling the valve it in response to changes in temperature ofthe cylinders II, as well as in response to changes in presure of the supplied mixture of fuel and a5 compressed air. Both temperature and fuel and air pressure aifect to a considerable extent the safety and the efilciency of internal combustion engines and these variables of temperature and pressureare especially apparent in the opera- 40 tion of internal combustion engines on aircrafts because the cooling eflect of the atmosphere, as well as the pressure of the supplied mixture of fuel and air, are considerably reduced as an aircraftriseatohigheraltitudeandviceveraa, areincreasedasanaircraftdescendstowarda sealevel. Thus,itwillbereadilyunderstood that a properly supercharged internal combustion engine of an aircraft firing at an altitude of 10,000 feet would be excessively supercharged as the airplane descends towards sea level, were'not means provided for automatically controlling the superchar lns pressure.

The arrangement in the present example (Pig.

3) includes two devices, a pressure responsive as device and a temperature responsive device 2|. The pressure responsive device 20 comprises a bellows 22 held on. a support 23 and biased towards said support by a spring 24 disposed between the upper end of the bellows 22 and a fixed support 25. The bellows 22 is connected by a pipe 26 to the inlet manifold M whereby the bellows expands and collapses as the pressure in the manifold M rises and drops respectiyely. Similarly, the temperature responsive device 2| comprises a bellows 21 and a spring 28 corresponding to and similarly arranged as the bellows 22 and the spring 24 of the device 20. The bellows 21 is connected by a pipe 29 to a bulb 30 suitably secured to and in thermal contact with the cylinder structure I. The bulb 30 contains a fluid, preferably a liquid which evaporates as the temperature of the cylinder structure rises. The evaporation effects an increase in pressure in the bellows 21 whereby the latter expands. The bellows 22 and 21 have upper ends connected by links 3| and 32 respectively to the ends of a lever 33, which latter has an intermediate point pivoted by a link 34 to a reversing switch 35. The reversing switch 35 serves to connect, disconnect and reverse a reversing motor 36. The circuit for the motor includes a source of electric energy 31 and two limiting switches 38 and 39. If the reversing switch 35 is moved upward in response to increase in pressure or temperature, it efl'ects closing of the motor circuit through an upper contact 40 and an intermediate contact 4| whereby the motor is rotated in a direction to effect closing movement of the valve I3, and when the reversing switch 35 is moved downward, due to a decrease in pressure or temperature or both pressure and temperature, the switch engages the intermediate contact 4| and a lower contact 42 whereby the motor circuit is closed with the motor running in reverse direction, effecting opening movement of the valve l3. An arrangement of this kind is disclosed and more fully described in my copending application, Serial No. 451,107, filed May 9, 1930, and assigned. to the same assignee.

The elements connecting the reversing motor 36 with the valve I3 through the intermediary of the hand-operated lever l1, the link l5 and the valve arm H are arranged to permit the following functions: First, manual setting of the control at any point below the predetermined conditions for which the automatic member of the control is set; second, limiting such seting of the manual control to said predetermined conditions; third, automatic governing by the control to maintain the conditions for which it is set; fourth, temporary surpassing of the predetermined conditions by application of abnormal force on the manual control member for emergency use; and fifth, automatic return of the control to the governing position immediately upon the removal of the abnormal force on the manual control. The motor 36 and the elements connecting this motor with the lever l1 are arranged to form a single control unit. This control unit comprises a frame having a rear plate 43 and a front plate 44. The rear plate 43 has an opening surrounded by an annular flange or supporting member 45 which is integrally united with the plate 43. The plate, has an opening fitting the outer end of the flange 45. The two plates forming the frame are united by bolts 46, 41, Fig. 2, and in addition, the plates are provided with openings 48, 49 for securing the end of the handle l9.

unit to a suitable support which may be an .element of an aircraft structure, not shown. The opening defined by the annular portion l6 of the manually controlled lever H has a sliding fit with the outer surface of the supporting member 45 and, as best shown in Fig. 3, the lever I1 is held on a front portion of said supporting member 45 adjacent the front plate 44. An automatically movable element or gear 55 is rotatably arranged on the. supporting member 45 adjacent the rear plate 43. The gear '50 has a web 5| with openings 52 to make the gear as light as possible and defining an annular recess 53. The gear 50 may be rotated in either direction by, the reversing motor 36 through the intermediary of speed reducing means comprising two worm gearings 54 and 55 and a worm 56, which latter meshes with the teeth 'of the gear 50. The arrangement so far described effects rotation of the gear 50 in counter clock-' wise and clockwise direction in response to increase and decrease respectively in pressure and temperature of the superchargedinternal combustion engine.

The transmission of rotary movement or torque from the gear 50 to the manually operated lever I1 is effected by coupling means comprising a connecting lever 51, a dog 56 held on the lever 51 and normally engaging the teeth of the gear 50 and a yieldable or resilient connecting member, more specifically a spring 59 between the levers 51 and H. The lever 51 is disposed between the lever l1 and the wheel 50 and has an annular portion 60 (Fig. 4) similar to the portion |8 of the lever H, which portion 65 is rotatably secured to the supporting member 45. The spring 59 for connecting the connecting means, that is, the lever 51 and the dog 58, with the manually operated lever I1 is disposed in the aforementioned annular recess 52 of the gear 50. The spring in the present instance comprises a single turn with bent ends engaging opposite edges of the two levers to force them into alinement. The aforementioned dog 56 is slidably arranged in a casing 6| and biased towards the gear 55 by a compression spring 62 in said casing (Fig. 6). The dog is prevented from-dropping out of the casing by a pin 63 secured to the dog and slidably arranged in a slot 64 of the casing 6|.

lever 51 by means of a pivot 61. Under certain conditions the casing 6| is permitted to turn counterclockwise about the pivot 61 to permit disengagement between the dog 55 and the gear 50 but the casing 6| is always prevented from turning clockwise fromthe position indicated in Figs. 2 and 4 by the provision of a stop 66 in the form of a pin secured to the lateral projection 66 of the connecting lever 51. Thus, with the arrangement so far described, rotation of the gear 50 in counterclockwise direction, that is, towards closing position of the valve l3, will be always effective as regards the transmission of torque from the gear through the dog to the connecting lever 51. To render the transmission of torque or movement effective with the gear 50 rotatingin clockwise direction, that is, towards opening position of the valve l3, means are provided which normally prevent the casing 6| for holding the dog 56 from turning in counterclockwise direction about the pivot 61. This means comprises a stop 69 secured to the lower The i'andle |9 which The casing 6| has a lateral projection 65 held on a.-1ateral projection 66 of the connecting forms an extension of the lever I1 is pivotally secured to the upper end of the lever l1 by a screw and nut 10. A portion ll of the handle carrying at its lower end the stop II is normally in alinement with the lever l1 and in this case the stop 69 engages the upper end of the casing 6|, preventing tilting or turning movement'of the latter. The portion ll of the handle may be turned about the pivotal connection 10 whereby the stop 69 is moved away from the casing ll and permits the latter to turn in counterclockwise direction (Fig. 5) about the pivot 61. The turning movement of the handle portion II is limited by a pin 12 secured to the portion II and projecting through a slot (Fig. 5) I! of the lever II. A nut 14 is secured to the front portion of the pin 12 in order to keep the adjacent surfaces of the handle portion II and the upper portion of the lever II in sliding engagement.

The normal automatic operation of the mechanism is as follows: An increase in pressure in the manifold II or temperature of the cylinder structure It causes closing movement of the reversing switch due to the expanding of the bellows 22 or 21, and the closing of the switch It, as pointed out above, causes operation of the reversing motor 88 in a direction to turn the wheel through the intermediary of the worm g earings 5 4 and II and the worm l. in counterclockwise direction. Turning movement of the wheel 50 in this direction causes the dog with the connecting lever I! to travel towards the I left, that is, in the same direction as the wheel W. This movement of the dog and the connecting leverJ'l is transmitted to the manually movable lever 11 by the biasing spring II, which latter, as stated before, maintains under normal conditions alinement or a definite angular relation between the connecting lever 51 and the manually movable lever II or, from another viewpoint, the spring It causes the manually movable lever to follow the movement of the connecting lever. In the present instance, where the connecting lever I1 is moved in counterclockwise direction, it causes the manually movable lever to move in the same direction and to the same extent, whereby the valve ll being connected to the connecting portion it of the manually movable lever is moved towards closing direction.

This closing of the valve I! in the present example reduces the flow' of fuel and compressed air to the manifold H and the cylinders of the engine, whereby the pressure in the manifold and the temperature of the cylinder structure are reduced.

The operation during a decrease in pressure or temperature, or both, is similar with the different elements moving in opposite direction to effect opening movement of the valve.

-The arrangement of the manually movable lever l'l, its connecting portion ll, the link II and the lever arm I4 is such that the flow of mixture through the conduit if changes in proportion to the movement of the manually movable lever l'l. The valve I! has a non-linear characteristic, that is, the flow through the conduit 12 does not change in proportion to the movement of the valve. When the valve is fully open, a slight closing movement of the valve has little effect on the flow, whereas when the valve I3 is closed, such slight movement towards openin'g considerablychanges the rate of flow. This non-linear characteristic of the valve is compensated by providing the lever l'l, its connecting portion IS. the link II. and the lever arm II in a definite angular relation so that, as stated above, uniform movement of the lever I1 eil'ects uniform change of flow through the conduit II. The connecting portion I6 is provided with numerous openings 14' to permit adjustability between the link II and. the portion I 62 In the present instance, as shown in Fig. 1, the link i5 is connected to the outer opening Il The mechanism also includes means for rendering the automatic control ineffective as soon as the valve has been moved towards closing direction into a predetermined position because, as stated above, it is undesirable, especially where the mechanism serves for operating an aircraft engine, to permit the automatic control to completely shut the valve. This is accomplished by a cam 15 secured to the rear plate 43 of the frame by screws 16 and I1 (Fig. 2). The

cam 15 surrounds a portion of the gear and has a cam surface It. The dog 58, as will be noted in Fig. 3, has a slotted portion I9 which rides on the cam II and in a certain valve position is movement will be effected automatically untilthe valve reaches a certain position indicated in Fig. 2 by a dash-dotted line A. In this position the dog Bl has been removed from its engagement by compression of the spring 82 with the gear ill and further rotation of the gear in counterclockwise direction therefore will not aflect the valve position, that is, will not effect further closing movement of the valve. Such further closing movement and complete closing of the valve is possible only by the manipulation of the manually operated lever l1. I1 is moved towards closing position it engages in the end position an actuating member '0 of the limiting switch 38 and effects opening of the motor circuit. The limiting switches 38 and I! are mounted on the rear plate ll of the frame. Whereas the member is disposed in the plane of the lever IT, a corresponding member ll of the switch 39 is disposed in the plane of the connecting means, 58, 6| and said member Ul is actuated to open the switch I.

when said connecting means is moved into full now a certain condition, for instance an emer-' gency condition, calls for further opening of the valve, such further opening may be effected at any time by moving the manually'operated lever I'I towards the right. This movement, however. has to be eifected against the resistance or biasing force of the spring 59, that is, if the operator wants to open the valv further than is desirable with respect to safety and eiliciency of the engine he has to apply aconsiderable force andthe valve will remain in the new position only as long as the operator applies such force to the handle IQ of the lever I'I. Such a condition is indicated in Fig. 4" of the drawing in which an arrow indicates the force applied to the handle I! by the operator. As soon as the operator releases the handle l9, that is removes said force, the handletogether with the lever II returns automatically into alinement with the connecting lever 51, that is into the position shown in Fig. 2. This is an important feature If the lever automatic control means becomes effective in-- stantly as long as the dog 58 engages the gear 50.

Under certain conditions it is desirable to disconnect or render inoperative the automatic control to prevent further opening of the valve. This is accomplished merely by tilting the handle I 3 as indicated in Fig. 5. In this position, clockwise movement. of the gear 50 calling for further valve opening is not transmitted to the connecting means including the lever 51 and the dog 58.

If, however, in the position of Fig. 5 changing conditions call for closing of the valve, causing counterclockwise rotation of the gear 50, such rotation is transmitted through the dog 58 to the connecting lever 51, irrespective of the tilted position of the handle portion ii. As clearly indicated in Fig. 5, with the casing 6| in tilted position, the dog 58 still projects between two' teeth of the gear 50. Clockwise rotation of the gear, however, causes the dog, and hence the casing (ii, to move in a counterclockwise manner about the pivot 68, thus raising the dog 50 out of the teeth in the manner of an ordinary ratchet, whereas counterclockwise rotation of the gear 50 at first efiects straightening out of the dog, that is, bringing the dog 58 and the casing 6| into alinement with the levers 51, and thereafter effects counterclockwise movement of connecting lever 51, effecting the same movement of the lever l1 and resulting in closing movement of the valve i3.

Let us assume in the position indicated in Fig. 5 the valve l3 be 50% open, whereas safety and efficiency of the engine would permit a 100% or full opening of the valve l3. It under such condition the operator wishes to move the valve into a position, 75% open, he applies a slight pressure to the left side 01' the handle l9. bringing into alinement the handle portion H and the lever I! to render the stop 58 effective to cause engagement between the dog 58 and the ear 50. When this is accomplished the automatic control will effect turning movement of the gear towards valve opening position and as soon as the valve is approximately 75% open, the operator renders again the automatic control inoperative by a slight pressure to the right side of the. handle H to remove the stop 88 from the dog casing 6|. As will be noted, the righthand upper edge of the casing 5| and the lefthand lower edge of the stop 89 (Fig. 5) are cut away to permit engagement anddisengagement between the casing 6| and the stop 69.

With my invention I have accomplished an improved construction and arrangement of contr ol mechanisms for manually and automatically controlling a regulating or control element 01 an engine. The automatic control causes operation of the engine at greatest emciency and maximum safety. This is particularly important and advantageous in cases where the engine is subject to considerable variation in operating conditions. The operator is relieved of the necessity of watching closely the operation or the engine in order to maintain maximum safe load. At the same time, however, the operator is in a position to readily eiIect changes in the setting of the regulated element by the automatic controi, and the arrangement is such as to enable the-operator to difierentiate between the manual operation beyond and below safe load condition because manual movement of the regulated element beyond safe load condition has to be e!- fected by the continuous application 01 considerable force. The manually movable element of the control mechanism is normally in alinement or in definite relative position with an element 0! the automatic control means which has the distinct advantage that any change called for by the automatic control means becomes effective immediately. The automatic control means is automatically put out of operation or rendered ineffective as the valve reaches a certain closing position, and the automatic control may be rendered inefiective in the direction of safe movement by a simple manipulation of the handie ot the manually movable lever.

Having described the method or operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:-

1. In an engine control mechanism, the combination of ,a manually movable element having a handle for moving it and a connecting portion for moving a controlled member, another element to be moved automatically in response to changes of a certain operating condition, and coupling means for transmitting motion between said elements and for normally maintaining a definite relative position between said elements, the coupling means including a resilient member connected to the manually movable element to cause said element to return into said relative position when manually moved out of said relative position, and means for automatically disengaging the coupling means to render the automatically operated element inoperative.

2. In an engine control mechanism, the combination of a manually movable element having a handle for moving it and a connecting portion for moving a controlled member, another element to be moved automatically in response to changes of a certain operating condition, coupling means for transmitting motion between said elements and for normally maintaining a definite relative position between said elements, and means for automatically disengaging the coupling means to render movement of the automatically actuated element ineffective within a predetermined range of its total movement.

3. In an engine control mechanism, the combination of a manually movable element having a handle for moving it and a connecting portion for moving a controlled member, another element to be moved automatically in response to changes of a certain operating condition, coupling means for transmitting motion between said elements and for normally maintaining a dellnite relative position between said elements, and means for rendering the coupling means inoperative in response to movement of the automatically operated element beyond a fixed position.

4. In an engine control mechanism, the combination of an engine member to be controlled an element having a handle for manually moving the element and a portion positively connecting the element to the engine member to be controlled, another element to be moved automatically in response to certain operating conditions, and. coupling means for moving the first named element in response to movement of the other element, said coupling means comprising means including a pawl engaging the other element, a connecting lever supporting the pawl and a spring connecting said lever to the first named element and normally biasing said means into a definite relative position with respect to the first namedelement, said coupling means permitting manual movement of the engine member without interfering with the operation of the other element.

5. In an engine control mechanism, the combination of a rotatable element having a handle for manually moving the element and a portion for positively connecting the element to an engine member to be controlled, another element to be moved automatically in response to certain operating conditions, and coupling means for movingthe first named element in response to movement of the other element and permitting manual movement of the rotatable element without interfering with the automatic operation of the other element, said coupling means comprising a rotatable connecting lever engaging the other element and a spring biasing the connecting lever into alinement with the first named element whereby movement of the connecting lever in response to movement of the other element effects instantaneous movement of the first named element.

6. In an engine control, mechanism, the combination of an .element having a handle for manually moving the element and a portion for connecting the element to an engine member to be controlled, another element to be moved automatically in response to certain operating conditions, coupling means for moving the first named element in response to movement of the other element, said coupling means comprising a connecting lever, a movable member on the lever engaging the other element, a stop on the handle engaging said movable member, and resilient means biasing the connecting lever into alinement with the first named lever, the handle beingpivoted to the first named element so that turnins movement of the handle about "its pivot causes the stop to be removed from said movable memher and the coupling rendered ineffective.

7. In an engine control mechanism, the combination of a lever having a handle for manually moving it and a portion for connecting it to an engine member to be controlled, a gear to be controlled automatically, and coupling means for transmitting movement of the gear to the lever comprising connecting means engaging the gear and resilient means intermediate the connecting means and the lever to move the lever in response to gear movement and to bias the lever into a definite relative position to the gear, said resilient means permitting manual movement of the lever in one direction by the manual application of a considerable form.

8. In an engine control mechanism, the 'combination of a lever having a handle for manually moving it and a portion for connecting it to an engine member to be controlled, a gear to be controlled automatically, and coupling means for transmitting movement of the gear to the lever comprising a connecting lever, a dog on theconnecting lever engaging the gear and a spring biasing the connecting. lever into alinement with the first named lever.

9. In an engine control mechanism, the combination of a lever having a handle for manually moving it and a portion for connecting it to an connecting lever engaging the gear and a spring' biasing the connecting lever into alinement with the first named lever, and means for rendering the automatic control inoperative in certain range of gear movement comprising cam means cooperating with the dog and disengaging the dog from the gear as the gear with the dog reaches a certain position.

10. In an engine control mechanism, the combination of a lever having a handle for manually moving it and a portion for connecting it to an engine member to be controlled, a gear to be controlled automatically, coupling means for transmitting movement of the gear to the lever comprising a connecting lever, a dog on the connecting lever engaging the gear and a spring biasing the connecting lever into alinement with the first named lever, and means for rendering the automatic control inoperative in at least one direction of gear movement comprising a movable stop secured to the handle for normally holding the dog in cooperative relation with the gear. Y

11. In an engine control mechanism, the combination of a lever, a handle pivoted to the lever for manually moving it and a portion on the lever for connecting it to an engine member to.

be controlled, a frame having a support for rotatably supporting the lever, arotatable gear on the support to be moved automatically in response to changes of a certain operating condition, a connecting lever rotatably supported on the support, a dog pivotally secured to the connecting lever, a stop on said handle for effecting engagement between the dog and the gear, and a spring biasing the connecting lever into alinement with the manually movable lever.

12. In an engine control mechanism, a unit comprising in combination a frame, a manually movable leverhaving a portion rotatably supported on the frame, a handle pivoted to said lever portion and another portion united with .the first named portion for connecting the lever to an engine member to be controlled, a gear concentrically supported with the lever on the frame, a motor and speed reducing means secured to the frame for driving the gear in response to changes of a certain operating condition, and coupling means including a spiral spring disposed in an annular recess of the gear for moving the lever in response to gear movement.

13. In an engine control mechanism, the combination of a controllable engine element, a manually movable lever positively connected to the element, and means for automatically moving the lever in response to a certain operating condition, said means including a rotatable gear, a connecting lever connected to the gear and a resilient member normally biasing the movable lever into a definite position relative to the connecting lever, said resilient member permitting the movable lever to be moved manually by the application of a considerable force without interfering with the operation of the means for automatically moving the lever.

14. In an engine control mechanism, the combination of a valve for controlling the flow of an actuating fluid to an engine, a .pivotally supported manually movable lever, means connecting a portion of the lever to the valve, said means lever movement causes uniform change in flow, and means for automatically moving the lever in response to changes of a certain operating condition comprising a' spring connected to the lever to permit manual valve opening movement beyond the position set by the automatic operating means against the biasing force of said spring, and means including said spring for returning the manually movable lever when manually moved beyond the position set by -the automatic operating means to said set position as soon as the force exerted on the lever is removedl 15. In an engine control mechanism, the combination of manually controlled means, an automatically controlled element limiting said manually controlled means to a predetermined condition of engine operation, and means including a spring connecting said manually controlled means to said automatically controlled element, said spring permitting movement of the manually controlled means by the application of a force sufiicient to overcome the biasing force of said spring without interfering with the operation and the position of the automatically controlled element.

16. m an engine control mechanism, the combination of a machine element to be controlled, manually movable means positively secured to the machine element for manually positioning the element, another element, means for automatically positioning the other element in response to certain operating conditions, and connecting means including a yieldable member connecting the other element to the manually movable means to effect control of the machine element in response to movement of the other element through the intermediary of the manually movable means, said connecting means normally effecting a definite relative position between the manually movable means and the other element and permitting actuation of the manually movable means without interfering with the operation of the other element.

SAMUEL R. PUFF'ER. 

